feat: enhance error handling and configuration validation

- Added a global exception handler to log unhandled exceptions and return a generic 500 JSON response without exposing details to the client.
- Updated the configuration to validate the `DATABASE_URL` format, ensuring it starts with `sqlite://` or `postgresql://`, and log warnings for invalid formats.
- Introduced safe parsing for numeric environment variables (`HTTP_PORT`, `INIT_DATA_MAX_AGE_SECONDS`) with defaults on invalid values, including logging warnings for out-of-range values.
- Enhanced the duty schedule parser to enforce limits on the number of schedule rows and the length of full names and duty strings, raising appropriate errors when exceeded.
- Updated internationalization messages to include generic error responses for import failures and parsing issues, improving user experience.
- Added unit tests to verify the new error handling and configuration validation behaviors.

duty_teller/handlers/commands.py

@@ -67,7 +67,8 @@ async def set_phone(update: Update, context: ContextTypes.DEFAULT_TYPE) -> None:
     phone = " ".join(args).strip() if args else None
     telegram_user_id = update.effective_user.id
 
-    def do_set_phone() -> str | None:
+    def do_set_phone() -> tuple[str, str | None]:
+        """Returns (status, display_phone). status is 'error'|'saved'|'cleared'. display_phone for 'saved'."""
         with session_scope(config.DATABASE_URL) as session:
             full_name = build_full_name(
                 update.effective_user.first_name, update.effective_user.last_name
@@ -82,16 +83,20 @@ async def set_phone(update: Update, context: ContextTypes.DEFAULT_TYPE) -> None:
             )
             user = set_user_phone(session, telegram_user_id, phone or None)
             if user is None:
-                return "error"
+                return ("error", None)
             if phone:
-                return "saved"
-            return "cleared"
+                return ("saved", user.phone or config.normalize_phone(phone))
+            return ("cleared", None)
 
-    result = await asyncio.get_running_loop().run_in_executor(None, do_set_phone)
+    result, display_phone = await asyncio.get_running_loop().run_in_executor(
+        None, do_set_phone
+    )
     if result == "error":
         await update.message.reply_text(t(lang, "set_phone.error"))
     elif result == "saved":
-        await update.message.reply_text(t(lang, "set_phone.saved", phone=phone or ""))
+        await update.message.reply_text(
+            t(lang, "set_phone.saved", phone=display_phone or "")
+        )
     else:
         await update.message.reply_text(t(lang, "set_phone.cleared"))